Methods for treating diabetes

ABSTRACT

This invention describes methods of treating or preventing diabetes in obese type II diabetic patients. Specifically, methods of treating obese type II diabetics with varying levels of endogenous circulating leptin are claimed.

CROSS REFERENCE

This application claims the benefit of U.S. Provisional Application Ser. No. 60/000,718 filed Jun. 30, 1995.

FIELD OF THE INVENTION

The present invention relates to the field of human medicine, particularly the treatment of diabetes. Most specifically, the invention relates to a method for treating obese, type II diabetics whose endogenous leptin levels are abnormally low or high.

BACKGROUND OF THE INVENTION

Diabetes mellitus is a metabolic disorder characterized by the failure of body tissues to store carbohydrates at the normal rate. Resistance to the action of insulin is the most important factor to type II diabetes. When this resistance exceeds the capacity of the beta cells to produce insulin, a person becomes diabetic. During the last 70 years people suffering from diabetes have been greatly aided by receiving controlled amounts of insulin.

Obesity, particularly upper body obesity, is often associated with non-insulin-dependent diabetes mellitus (NIDDM). These so called type II diabetics do not have an absolute requirement for insulin as their beta cells are able to secrete insulin, albeit often at diminished levels. In addition such patients are often obese and may demonstrate an inability to respond to insulin.

It is well known that a regimen of diet and exercise leading to weight loss is the best approach for treating obese type II diabetics. Unfortunately, these regimens are usually unsuccessful. Failure to loss weight may be due to genetically inherited factors that contribute to increased appetite, a preference for high calorie foods, reduced physical activity, and an increased lipogenic metabolism. People inheriting such genetic predispositions are prone to obesity and often become type II diabetics, regardless of their efforts to combat the condition.

The ob /ob mouse is a model of obesity and diabetes that is known to carry an autosomal recessive trait linked to a mutation in the sixth chromosome. Yiying zhang and co-workers published the positional cloning of the mouse gene (ob) linked with this condition. Yiying Zhang et al. Nature 372: 425-32 (1994). This report disclosed a gene coding for a 167 amino acid protein (hereinafter leptin) with a 21 amino acid signal peptide that is exclusively expressed in adipose tissue.

Physiologists have postulated for years that, when a mammal overeats, the resulting excess fat signals to the brain that the body is obese which, in turn, causes the body to eat less and burn more fuel. G. R. Hervey, Nature (London), 227: 629-631 (1969). This model of feedback inhibition is supported by parabiotic experiments, which implicate a circulating hormone controlling adiposity.

Based on recent in vivo experiments conducted under the inventor's supervision, leptin has now been shown to be an adiposity regulating hormone. Most importantly however, blood parameters monitored during these experiments quite unexpectedly demonstrated that treatment with leptin totally ameliorated the diabetic state of the research animals.

Moreover, circulating levels of leptin in obese individuals have been shown to vary widely. Consequently, it is now believed that certain subpopulations of obese type II diabetics are particularly amenable to treatment with leptin. Pharmacological agents which are biologically active and mimic the activity of leptin are therefore useful for treating obese type II diabetics, particularly those with abnormal levels of circulating leptin.

SUMMARY OF THE INVENTION

A method of treating or preventing diabetes mellitus which comprises administering to an obese type II diabetic an effective amount of leptin, leptin mimetic, fragment thereof, or a pharmaceutically acceptable salt thereof is claimed. In a preferred embodiment, the invention includes methods for treating obese type II diabetics having abnormal endogenous levels of circulating leptin.

DETAILED DESCRIPTION OF THE INVENTION

The terms and abbreviations used in this document have their normal meanings unless otherwise designated. For example "°C." refers to degrees Celsius; "N" refers to normal or normality; "mmol" refers to millimole or millimoles; "g" refers to gram or grams; "ml" means milliliter or milliliters; "M" refers to molar or molarity; "μg" refers to microgram or micrograms; and "μl" refers to microliter or microliters.

All amino acid or protein sequences, unless otherwise designated, are written commencing with the amino terminus ("N-terminus") and concluding with the carboxy terminus ("C-terminus"). "Base pair" or "bp" as used herein refers to DNA or RNA. The abbreviations A,C,G, and T correspond to the 5'-monophosphate forms of the deoxyribonucleosides (deoxy)adenine, (deoxy)cytidine, (deoxy)guanine, and (deoxy)thymine, respectively, when they occur in DNA molecules. The abbreviations U,C,G, and T correspond to the 5'-monophosphate forms of the ribonucleosides uracil, cytidine, guanine, and thymine, respectively when they occur in RNA molecules. In double stranded DNA, base pair may refer to a partnership of A with T or C with G. In a DNA/RNA, heteroduplex base pair may refer to a partnership of A with U or C with G. (See the definition of "complementary", infra.)

The terms "digestion" or "restriction" of DNA refers to the catalytic cleavage of the DNA with a restriction enzyme that acts only at certain sequences in the DNA ("sequence-specific endonucleases"). The various restriction enzymes used herein are commercially available and their reaction conditions, cofactors, and other requirements were used as would be known to one of ordinary skill in the art. Appropriate buffers and substrate amounts for particular restriction enzymes are specified by the manufacturer or can be readily found in the literature.

"Ligation" refers to the process of forming phosphodiester bonds between two double stranded nucleic acid fragments. Unless otherwise provided, ligation may be accomplished using known buffers and conditions with a DNA ligase, such as T4 DNA ligase.

The term "plasmid" refers to an extrachromosomal (usually) self-replicating genetic element. Plasmids are generally designated by a lower case "p" preceded and/or followed by letters and/or numbers. The starting plasmids herein are either commercially available, publicly available on an unrestricted basis, or can be constructed from available plasmids in accordance with published procedures. In addition, equivalent plasmids to those described are known in the art and will be apparent to the ordinarily skilled artisan.

The term "reading frame" means the nucleotide sequence from which translation occurs "read" in triplets by the translational apparatus of transfer RNA (tRNA) and ribosomes and associated factors, each triplet corresponding to a particular amino acid. A base pair insertion or deletion (termed a frameshift mutation) may result in two different proteins being coded for by the same DNA segment. To insure against this, the triplet codons corresponding to the desired polypeptide must be aligned in multiples of three from the initiation codon, i.e. the correct "reading frame" being maintained.

The term "expression vector system" as used herein refers to a recombinant DNA expression vector in combination with one or more trans-acting factors that specifically influence transcription, stability, or replication of the recombinant DNA expression vector. The trans-acting factor may be expressed from a co-transfected plasmid, virus, or other extrachromosomal element, or may be expressed from a gene integrated within the chromosome.

"Transcription" as used herein refers to the process whereby information contained in a nucleotide sequence of DNA is transferred to a complementary RNA sequence.

The term "transfection" as used herein refers to the taking up of an expression vector by a host cell whether or not any coding sequences are in fact expressed. Numerous methods of transfection are known to the ordinarily skilled artisan, for example, calcium phosphate co-precipitation, and electroporation. Successful transfection is generally recognized when any indication of the operation of this vector occurs within the host cell.

The term "transformation" as used herein means the introduction of DNA into an organism so that the DNA is replicable, either as an extrachromosomal element or by chromosomal integration. Methods of transforming bacterial and eukaryotic hosts are well known in the art, many of which methods, such as nuclear injection, protoplast fusion or by calcium treatment using calcium chloride are summarized in J. Sambrook, et al., MOLECULAR CLONING: A LABORATORY MANUAL, (1989).

The term "translation" as used herein refers to the process whereby the genetic information of messenger RNA is used to specify and direct the synthesis of a polypeptide chain.

The term "vector" as used herein refers to a nucleic acid compound used for the transformation of cells in gene manipulation bearing polynucleotide sequences corresponding to appropriate protein molecules which when combined with appropriate control sequences confer specific properties on the host cell to be transformed. Plasmids, viruses, and bacteriophage are suitable vectors. Artificial vectors are constructed by cutting and joining DNA molecules from different sources using restriction enzymes and ligases. The term "vector" as used herein includes Recombinant DNA cloning vectors and Recombinant DNA expression vectors.

The terms "complementary" or "complementarity" as used herein refers to pair of bases, purines and pyrimidines, that associate through hydrogen bonding in double stranded nucleic acid. The following base pairs are complementary: guanine and cytosine; adenine and thymine; and adenine and uracil.

The term "hybridization" as used herein refers to a process in which a strand of nucleic acid joins with a complementary strand through base pairing. The conditions employed in the hybridization of two non-identical, but very similar, complementary nucleic acids varies with the degree of complementarity of the two strands and the length of the strands. Such techniques and conditions are well known to practitioners in this field.

"Isolated amino acid sequence" refers to any amino acid sequence, however constructed or synthesized, which is locationally distinct from the naturally occurring sequence.

"Isolated DNA compound" refers to any DNA sequence, however constructed or synthesized, which is locationally distinct from its natural location in genomic DNA.

"Isolated nucleic acid compound" refers to any RNA or DNA sequence, however constructed or synthesized, which is locationally distinct from its natural location.

A "primer" is a nucleic acid fragment which functions as an initiating substrate for enzymatic or synthetic elongation.

The term "promoter" refers to a DNA sequence which directs transcription of DNA to RNA.

A "probe" as used herein is a nucleic acid compound or a fragment thereof which hybridizes with a complementary nucleic acid compound.

The term "stringency" refers to a set of hybridization conditions which may be modulated to vary the degree to which probes bind their complementary DNA strands.

The term "PCR" as used herein refers to the widely-known polymerase chain reaction employing a thermally-stable polymerase.

The phrase "reading frame" as used herein refers to the nucleotide sequence from which translation occurs "read" in triplets by the translational apparatus of tRNA, ribosomes and associated factors, each triplet corresponding to a particular amino acid. Because each triplet is distinct and of the same length, the coding sequence must be a multiple of three. A base pair insertion or deletion (termed a frameshift mutation) may result in two different proteins being coded for by the same DNA segment. To insure against this, the triplet codons corresponding to the desired polypeptide must be aligned in multiples of three from the initiation codon, i.e. the correct "reading frame" must be maintained. In the creation of fusion proteins containing a chelating peptide, the reading frame of the DNA sequence encoding the structural protein must be maintained in the DNA sequence encoding the chelating peptide.

The term "treating" describes the management and care of a patient for the purpose of combating the disease, condition, or disorder and includes the administration of leptin to prevent the onset of the symptoms or complications, alleviating the symptoms or complications, or eliminating the disease, condition, or disorder. Treating obese type II diabetics, for example, may include but is not limited to lowering elevated blood glucose and insulin levels, as well as lowering triglyceride and corticosterone levels in patients.

Obese--refers to a condition in which the individual has a body mass index (BMI) of greater than 27 kilograms per square meter.

Leptin--refers to the protein produced from the obesity gene following transcription and deletions of introns, translation to a protein and processing to the mature protein with secretory signal peptide removed, e.g., from the N-terminal valine-proline to the C-terminal cysteine of the mature protein. The mouse obesity protein and human obesity protein is published in zhang et al, Supra. The rat obesity protein is published in Murakami et al., Biochemical and Biophysical Research Comm. 209(3): 944-52 (1995). In the human, murine and rat obesity protein the Cys associated with di-sulfide formation is positions 96 and 145. However, particularly with the murine and human obesity protein, a desGln(28) variant has been observed. Hense, the Cys residues associated with di-sulfide bond formation may be at positions 95 or 96 and at position 145 or 146. Leptin may also be referred to throughout this specification as obesity protein, OB, or ob gene product. Native leptin therefore includes SEQ ID NOs:1-6 as follows. ##STR1## wherein: Xaa at position 28 is Gln or absent. ##STR2## wherein Xaa at position 28 is Gln or absent. ##STR3## wherein: Xaa at position 27 is Thr or Ala; and

Xaa at position 28 is Gln or absent. ##STR4##

Leptin mimetics are useful in the presently claimed methods such as those described in Basinski et al., in U.S. application Ser. No. 08/383,638, filed Feb. 6, 1995, and Hanson M. Hsung and Dennis P. Smith, in U.S. application Ser. No. 08/445,305, (Attorney Docket Number X-10179), filed May 19, 1995 herein incorporated by reference and shown in SEQ ID NOs: 7 and 8. More preferred antidiabetic proteins useful in the present invention include the native leptins shown in SEQ ID NOs: 1-6

Those skilled in the art will recognize that certain amino acids are prone to rearrangement. For example, Asp may rearrange to aspartimide and isoasparigine as described in I. Schon, et al., International Journal of Peptide and Protein Research, 14: 485-94 (1979) and references cited therein. These rearrangement derivatives are included within the scope of the present invention.

In addition to the above identified protein sequences, it is frequently considered expeditious to prepare such anti diabetic proteins with a one or two amino acid leader sequence, especially with a methionine containing leader. Two frequently employed leaders are Met-Arg and Met-Asp. Such proteins may be identified infra as Met-Arg-leptin or Met-Asp-leptin or may be identified by Met-Arg-SEQ ID NO:X, where X is 1 to 8.

Leptin mimetics and fragments are also useful in the methods of the present invention. Leptin mimetics and fragments are generally defined as follows: ##STR5## wherein: Xaa at position 22 is Asn, Asp or Glu;

Xaa at position 27 is Thr or Ala;

Xaa at position 28 is Gln, Glu, or absent;

Xaa at position 54 is Met or Ala;

Xaa at position 68 is Met or Leu;

Xaa at position 72 Asn, Asp or Glu;

Xaa at position 77 is Ser or Ala;

Xaa at position 118 is Gly or Leu;

said protein having at least one substitution selected from the group consisting of:

His at position 97 is replaced with Ser or Pro;

Trp at position 100 is replaced with Gln, Ala or Leu;

Ala at position 101 is replaced with Thr or Val;

Ser at position 102 is replaced with Arg;

Gly at position 103 is replaced with Ala;

Glu at position 105 is replaced with Gln;

Thr at position 106 is replaced with Lys or Ser;

Leu at position 107 is replaced with Pro;

Asp at position 108 is replaced with Glu; or

Gly at position 111 is replaced with Asp.

Preferably, leptin mimetics are as follows: ##STR6## wherein: Xaa at position 27 is Thr or Ala;

Xaa at position 77 is Ser or Ala;

Xaa at position 118 is Gly or Leu;

said protein having at least one substitution, preferably having one to five substitutions and, most preferably, one to two substitutions selected from the group consisting of:

His at position 97 is replaced with Ser;

Trp at position 100 is replaced with Ala;

Ala at position 101 is replaced with Thr;

Glu at position 105 is replaced with Gln;

Thr at position 106 is replaced with Lys;

Leu at position 107 is replaced with Pro;

Asp at position 108 is replaced with Glu; or

Gly at position 111 is replaced with Asp.

Examples of preferred leptins useful in the present invention include proteins of SEQ ID NO:8, wherein Xaa at position 27 is Thr; Xaa at position 77 is Ser; Xaa at positions 118 is Gly; and the amino acid residues at positions 97, 100, 101, 105, 106, 107, 108, and 111 are as Table I. The native human sequence is provided as a comparison to the proteins employed in the methods of the present invention.

                  TABLE I                                                          ______________________________________                                                Amino Acid Position                                                     Compound 97     100    101  105  106  107  108  111                            ______________________________________                                         native human                                                                            His    Trp    Ala  Glu  Thr  Leu  Asp  Gly                            1        Ser    Trp    Ala  Glu  Thr  Leu  Asp  Gly                            2        His    Gln    Ala  Glu  Thr  Leu  Asp  Gly                            3        His    Trp    Thr  Glu  Thr  Leu  Asp  Gly                            4        His    Trp    Ala  Gln  Thr  Leu  Asp  Gly                            5        His    Trp    Ala  Glu  Lys  Leu  Asp  Gly                            6        His    Trp    Ala  Glu  Thr  Pro  Asp  Gly                            7        His    Trp    Ala  Glu  Thr  Leu  Glu  Gly                            8        His    Trp    Ala  Glu  Thr  Leu  Asp  Asp                            9        Ser    Gln    Ala  Glu  Thr  Leu  Asp  Gly                            10       Ser    Trp    Thr  Glu  Thr  Leu  Asp  Gly                            11       Ser    Trp    Ala  Gln  Thr  Leu  Asp  Gly                            12       Ser    Trp    Ala  Glu  Lys  Leu  Asp  Gly                            13       Ser    Trp    Ala  Glu  Thr  Pro  Asp  Gly                            14       Ser    Trp    Ala  Glu  Thr  Leu  Glu  Gly                            15       Ser    Trp    Ala  Glu  Thr  Leu  Asp  Asp                            16       His    Gln    Thr  Glu  Thr  Leu  Asp  Gly                            17       His    Gln    Ala  Gln  Thr  Leu  Asp  Gly                            18       His    Gln    Ala  Glu  Lys  Leu  Asp  Gly                            19       His    Gln    Ala  Glu  Thr  Pro  Asp  Gly                            20       His    Gln    Ala  Glu  Thr  Leu  Glu  Gly                            21       His    Gln    Ala  Glu  Thr  Leu  Asp  Asp                            22       His    Trp    Thr  Gln  Thr  Leu  Asp  Gly                            23       His    Trp    Thr  Glu  Lys  Leu  Asp  Gly                            24       His    Trp    Thr  Glu  Thr  Pro  Asp  Gly                            25       His    Trp    Thr  Glu  Thr  Leu  Glu  Gly                            26       His    Trp    Thr  Glu  Thr  Leu  Asp  Asp                            27       His    Trp    Ala  Gln  Lys  Leu  Asp  Gly                            28       His    Trp    Ala  Gln  Thr  Pro  Asp  Gly                            29       His    Trp    Ala  Gln  Thr  Leu  Glu  Gly                            30       His    Trp    Ala  Gln  Thr  Leu  Asp  Asp                            31       His    Trp    Ala  Glu  Lys  Pro  Asp  Gly                            32       His    Trp    Ala  Glu  Lys  Leu  Glu  Gly                            33       His    Trp    Ala  Glu  Lys  Leu  Asp  Asp                            34       His    Trp    Ala  Glu  Thr  Pro  Glu  Gly                            35       His    Trp    Ala  Glu  Thr  Pro  Asp  Asp                            36       His    Trp    Ala  Glu  Thr  Leu  Glu  Asp                            37       Ser    Gln    Thr  Glu  Thr  Leu  Asp  Gly                            38       Ser    Gln    Ala  Gln  Thr  Leu  Asp  Cly                            39       Ser    Gln    Ala  Glu  Lys  Leu  Asp  Gly                            40       Ser    Gln    Ala  Glu  Thr  Pro  Asp  Gly                            41       Ser    Gln    Ala  Glu  Thr  Leu  Glu  Gly                            42       Ser    Gln    Ala  Glu  Thr  Leu  Asp  Asp                            43       Ser    Trp    Thr  Gln  Thr  Leu  Asp  Gly                            44       Ser    Trp    Thr  Glu  Lys  Leu  Asp  Gly                            45       Ser    Trp    Thr  Glu  Thr  Pro  Asp  Gly                            46       Ser    Trp    Thr  Glu  Thr  Leu  Glu  Gly                            47       Ser    Trp    Thr  Glu  Thr  Leu  Asp  Asp                            48       Ser    Trp    Ala  Gln  Lys  Leu  Asp  Gly                            49       Ser    Trp    Ala  Gln  Thr  Pro  Asp  Gly                            50       Ser    Trp    Ala  Gln  Thr  Leu  Glu  Gly                            51       Ser    Trp    Ala  Gln  Thr  Leu  Asp  Asp                            52       Ser    Trp    Ala  Glu  Lys  Pro  Asp  Gly                            53       Ser    Trp    Ala  Glu  Lys  Leu  Glu  Gly                            54       Ser    Trp    Ala  Glu  Lys  Leu  Asp  Asp                            55       Ser    Trp    Ala  Glu  Thr  Pro  Glu  Gly                            56       Ser    Trp    Ala  Glu  Thr  Pro  Asp  Asp                            57       Ser    Trp    Ala  Glu  Thr  Leu  Glu  Asp                            58       His    Gln    Thr  Gln  Thr  Leu  Asp  Gly                            59       His    Gln    Thr  Glu  Lys  Leu  Asp  Gly                            60       His    Gln    Thr  Glu  Thr  Pro  Asp  Gly                            61       His    Gln    Thr  Glu  Thr  Leu  Glu  Gly                            62       His    Gln    Thr  Glu  Thr  Leu  Asp  Asp                            63       His    Gln    Ala  Gln  Lys  Leu  Asp  Gly                            64       His    Gln    Ala  Gln  Thr  Pro  Asp  Gly                            65       His    Gln    Ala  Gln  Thr  Leu  Glu  Gly                            66       His    Gln    Ala  Gln  Thr  Leu  Asp  Asp                            67       His    Gln    Ala  Glu  Lys  Pro  Asp  Gly                            68       His    Gln    Ala  Glu  Lys  Leu  Glu  Gly                            69       His    Gln    Ala  Glu  Lys  Leu  Asp  Asp                            70       His    Gln    Ala  Glu  Thr  Pro  Glu  Gly                            71       His    Gln    Ala  Glu  Thr  Pro  Asp  Asp                            72       His    Gln    Ala  Glu  Thr  Leu  Glu  Asp                            73       His    Trp    Thr  Gln  Lys  Leu  Asp  Gly                            74       His    Trp    Thr  Gln  Thr  Pro  Asp  Gly                            75       His    Trp    Thr  Gln  Thr  Leu  Glu  Gly                            76       His    Trp    Thr  Gln  Thr  Leu  Asp  Asp                            77       His    Trp    Thr  Glu  Lys  Pro  Asp  Gly                            78       His    Trp    Thr  Glu  Lys  Leu  Glu  Gly                            79       His    Trp    Thr  Glu  Lys  Leu  Asp  Asp                            80       His    Trp    Thr  Glu  Thr  Pro  Glu  Gly                            81       His    Trp    Thr  Glu  Thr  Pro  Asp  Asp                            82       His    Trp    Thr  Glu  Thr  Leu  Glu  Asp                            83       His    Trp    Ala  Gln  Lys  Pro  Asp  Gly                            84       His    Trp    Ala  Gln  Lys  Leu  Glu  Gly                            85       His    Trp    Ala  Gln  Lys  Leu  Asp  Asp                            86       His    Trp    Ala  Gln  Thr  Pro  Glu  Gly                            87       His    Trp    Ala  Gln  Thr  Pro  Asp  Asp                            88       His    Trp    Ala  Gln  Thr  Leu  Glu  Asp                            89       His    Trp    Ala  Glu  Lys  Pro  Glu  Gly                            90       His    Trp    Ala  Glu  Lys  Pro  Asp  Asp                            91       His    Trp    Ala  Glu  Lys  Leu  Glu  Asp                            92       His    Trp    Ala  Glu  Thr  Pro  Glu  Asp                            93       Ser    Gln    Thr  Gln  Thr  Leu  Asp  Gly                            94       Ser    Gln    Thr  Glu  Lys  Leu  Asp  Gly                            95       Ser    Gln    Thr  Glu  Thr  Pro  Asp  Gly                            96       Ser    Gln    Thr  Glu  Thr  Leu  Glu  Gly                            97       Ser    Gln    Thr  Glu  Thr  Leu  Asp  Asp                            98       Ser    Gln    Ala  Gln  Lys  Leu  Asp  Gly                            99       Ser    Gln    Ala  Gln  Thr  Pro  Asp  Gly                            100      Ser    Gln    Ala  Gln  Thr  Leu  Glu  Gly                            101      Ser    Gln    Ala  Gln  Thr  Leu  Asp  Asp                            102      Ser    Gln    Ala  Glu  Lys  Pro  Asp  Gly                            103      Ser    Gln    Ala  Glu  Lys  Leu  Glu  Gly                            104      Ser    Gln    Ala  Glu  Lys  Leu  Asp  Asp                            105      Ser    G1n    Ala  Glu  Thr  Pro  Glu  Gly                            106      Ser    Gln    Ala  Glu  Thr  Pro  Asp  Asp                            107      Ser    Gln    Ala  Glu  Thr  Leu  Glu  Asp                            108      Ser    Trp    Thr  Gln  Lys  Leu  Asp  Gly                            109      Ser    Trp    Thr  Gln  Thr  Pro  Asp  Gly                            110      Ser    Trp    Thr  Gln  Thr  Leu  Glu  Gly                            111      Ser    Trp    Thr  Gln  Thr  Leu  Asp  Asp                            112      Ser    Trp    Thr  Glu  Lys  Pro  Asp  Gly                            113      Ser    Trp    Thr  Glu  Lys  Leu  Glu  Gly                            114      Ser    Trp    Thr  Glu  Lys  Leu  Asp  Asp                            115      Ser    Trp    Thr  Glu  Thr  Pro  Glu  Gly                            116      Ser    Trp    Thr  Glu  Thr  Pro  Asp  Asp                            117      Ser    Trp    Thr  Glu  Thr  Leu  Glu  Asp                            118      Ser    Trp    Ala  Gln  Lys  Pro  Asp  Gly                            119      Ser    Trp    Ala  Gln  Lys  Leu  Glu  Gly                            120      Ser    Trp    Ala  Gln  Lys  Leu  Asp  Asp                            121      Ser    Trp    Ala  Gln  Thr  Pro  Glu  Gly                            122      Ser    Trp    Ala  Gln  Thr  Pro  Asp  Asp                            123      Ser    Trp    Ala  Gln  Thr  Leu  Glu  Asp                            124      Ser    Trp    Ala  Glu  Lys  Pro  Glu  Gly                            125      Ser    Trp    Ala  Glu  Lys  Pro  Asp  Asp                            126      Ser    Trp    Ala  Glu  Lys  Leu  Glu  Asp                            127      Ser    Trp    Ala  Glu  Thr  Pro  Glu  Asp                            128      His    Gln    Thr  Gln  Lys  Leu  Asp  Gly                            129      His    Gln    Thr  Gln  Thr  Pro  Asp  Gly                            130      His    Gln    Thr  Gln  Thr  Leu  Glu  Gly                            131      His    Gln    Thr  Gln  Thr  Leu  Asp  Asp                            132      His    Gln    Thr  Glu  Lys  Pro  Asp  Gly                            133      His    Gln    Thr  Glu  Lys  Leu  Glu  Gly                            134      His    Gln    Thr  Glu  Lys  Leu  Asp  Asp                            135      His    Gln    Thr  Glu  Thr  Pro  Glu  Gly                            136      His    Gln    Thr  Glu  Thr  Pro  Asp  Asp                            137      His    Gln    Thr  Glu  Thr  Leu  Glu  Asp                            138      His    Gln    Ala  Gln  Lys  Pro  Asp  Gly                            139      His    Gln    Ala  Gln  Lys  Leu  Glu  Gly                            140      His    Gln    Ala  Gln  Lys  Leu  Asp  Asp                            141      His    Gln    Ala  Gln  Thr  Pro  Glu  Gly                            142      His    Gln    Ala  Gln  Thr  Pro  Asp  Asp                            143      His    Gln    Ala  Gln  Thr  Leu  Glu  Asp                            144      His    Gln    Ala  Glu  Lys  Pro  Glu  Gly                            145      His    Gln    Ala  Glu  Lys  Pro  Asp  Asp                            146      His    Gln    Ala  Glu  Lys  Leu  Glu  Asp                            147      His    Gln    Ala  Glu  Thr  Pro  Glu  Asp                            148      His    Trp    Thr  Gln  Lys  Pro  Asp  Gly                            149      His    Trp    Thr  Gln  Lys  Leu  Glu  Gly                            150      His    Trp    Thr  Gln  Lys  Leu  Asp  Asp                            151      His    Trp    Thr  Gln  Thr  Pro  Glu  Gly                            152      His    Trp    Thr  Gln  Thr  Pro  Asp  Asp                            153      His    Trp    Thr  Gln  Thr  Leu  Glu  Asp                            154      His    Trp    Thr  Glu  Lys  Pro  Glu  Gly                            155      His    Trp    Thr  Glu  Lys  Pro  Asp  Asp                            156      His    Trp    Thr  Glu  Lys  Leu  Glu  Asp                            157      His    Trp    Thr  Glu  Thr  Pro  Glu  Asp                            158      His    Trp    Ala  Gln  Lys  Pro  Glu  Gly                            159      His    Trp    Ala  Gln  Lys  Pro  Asp  Asp                            160      His    Trp    Ala  Gln  Lys  Leu  Glu  Asp                            161      His    Trp    Ala  Gln  Thr  Pro  Glu  Asp                            162      His    Trp    Ala  Glu  Lys  Pro  Glu  Asp                            163      His    Trp    Ala  Gln  Lys  Pro  Glu  Asp                            164      His    Trp    Thr  Glu  Lys  Pro  Glu  Asp                            165      His    Trp    Thr  Gln  Thr  Pro  Glu  Asp                            166      His    Trp    Thr  Gln  Lys  Leu  Glu  Asp                            167      His    Trp    Thr  Gln  Lys  Pro  Asp  Asp                            168      His    Trp    Thr  Gln  Lys  Pro  Glu  Gly                            169      His    Cln    Ala  Glu  Lys  Pro  Glu  Asp                            170      His    Gln    Ala  Gln  Thr  Pro  Glu  Asp                            171      His    Gln    Ala  Gln  Lys  Leu  Glu  Asp                            172      His    Gln    Ala  Gln  Lys  Pro  Asp  Asp                            173      His    Gln    Ala  Gln  Lys  Pro  Glu  Gly                            174      His    Gln    Thr  Glu  Thr  Pro  Glu  Asp                            175      His    Gln    Thr  Glu  Lys  Leu  Glu  Asp                            176      His    Gln    Thr  Glu  Lys  Pro  Asp  Asp                            177      His    Gln    Thr  Glu  Lys  Pro  Glu  Gly                            178      His    Gln    Thr  Gln  Thr  Leu  Glu  Asp                            179      His    Gln    Thr  Gln  Thr  Pro  Asp  Asp                            180      His    Gln    Thr  Gln  Thr  Pro  Glu  Gly                            181      His    Gln    Thr  Gln  Lys  Leu  Asp  Asp                            182      His    GIn    Thr  Gln  Lys  Leu  Glu  Gly                            183      His    Gln    Thr  Gln  Lys  Pro  Asp  Gly                            184      Ser    Trp    Ala  Glu  Lys  Pro  Glu  Asp                            185      Ser    Trp    Ala  Gln  Thr  Pro  Glu  Asp                            186      Ser    Trp    Ala  Gln  Lys  Leu  Glu  Asp                            187      Ser    Trp    Ala  Gln  Lys  Pro  Asp  Asp                            188      Ser    Trp    Ala  Gln  Lys  Pro  Glu  Gly                            189      Ser    Trp    Thr  Glu  Thr  Pro  Glu  Asp                            190      Ser    Trp    Thr  Glu  Lys  Leu  Glu  Asp                            191      Ser    Trp    Thr  Glu  Lys  Pro  Asp  Asp                            192      Ser    Trp    Thr  Glu  Lys  Pro  Glu  Gly                            193      Ser    Trp    Thr  Gln  Thr  Leu  Glu  Asp                            194      Ser    Trp    Thr  Gln  Thr  Pro  Asp  Asp                            195      Ser    Trp    Thr  Gln  Thr  Pro  Glu  Gly                            196      Ser    Trp    Thr  Gln  Lys  Leu  Asp  Asp                            197      Ser    Trp    Thr  Gln  Lys  Leu  Glu  Gly                            198      Ser    Trp    Thr  Gln  Lys  Pro  Asp  Gly                            199      Ser    Gln    Ala  Glu  Thr  Pro  Glu  Asp                            200      Ser    Gln    Ala  Glu  Lys  Leu  Glu  Asp                            201      Ser    Gln    Ala  Glu  Lys  Pro  Asp  Asp                            202      Ser    Gln    Ala  Glu  Lys  Pro  Glu  Gly                            203      Ser    Gln    Ala  Gln  Thr  Leu  Glu  Asp                            204      Ser    Gln    Ala  Gln  Thr  Pro  Asp  Asp                            205      Ser    Gln    Ala  Gln  Thr  Pro  Glu  Gly                            206      Ser    Gln    Ala  Gln  Lys  Leu  Asp  Asp                            207      Ser    Gln    Ala  Gln  Lys  Leu  Glu  Gly                            208      Ser    Gln    Ala  Gln  Lys  Pro  Asp  Gly                            209      Ser    Gln    Thr  Glu  Thr  Leu  Glu  Asp                            210      Ser    Gln    Thr  Glu  Thr  Pro  Asp  Asp                            211      Ser    Gln    Thr  Glu  Thr  Pro  Glu  Gly                            212      Ser    Gln    Thr  Glu  Lys  Leu  Asp  Asp                            213      Ser    Gln    Thr  Glu  Lys  Leu  Glu  Gly                            214      Ser    Gln    Thr  Glu  Lys  Pro  Asp  Gly                            215      Ser    Gln    Thr  Gln  Thr  Leu  Asp  Asp                            216      Ser    Gln    Thr  Gln  Thr  Leu  Glu  Gly                            217      Ser    Gln    Thr  Gln  Thr  Pro  Asp  Gly                            218      Ser    Gln    Thr  Gln  Lys  Leu  Asp  Gly                            219      His    Trp    Thr  Gln  Lys  Pro  Glu  Asp                            220      His    Gln    Ala  Gln  Lys  Pro  Glu  Asp                            221      His    Gln    Thr  Glu  Lys  Pro  Glu  Asp                            222      His    Gln    Thr  Gln  Thr  Pro  Glu  Asp                            223      His    Gln    Thr  Gln  Lys  Leu  Glu  Asp                            224      His    Gln    Thr  Gln  Lys  Pro  Asp  Asp                            225      His    Gln    Thr  Gln  Lys  Pro  Glu  Gly                            226      Ser    Trp    Ala  Gln  Lys  Pro  Glu  Asp                            227      Ser    Trp    Thr  Glu  Lys  Pro  Glu  Asp                            228      Ser    Trp    Thr  Gln  Thr  Pro  Glu  Asp                            229      Ser    Trp    Thr  Gln  Lys  Leu  Glu  Asp                            230      Ser    Trp    Thr  Gln  Lys  Pro  Asp  Asp                            231      Ser    Trp    Thr  Gln  Lys  Pro  Glu  Gly                            232      Ser    Gln    Ala  Glu  Lys  Pro  Glu  Asp                            233      Ser    Gln    Ala  Gln  Thr  Pro  Glu  Asp                            234      Ser    Gln    Ala  Gln  Lys  Leu  Glu  Asp                            235      Ser    Gln    Ala  Gln  Lys  Pro  Asp  Asp                            236      Ser    Gln    Ala  Gln  Lys  Pro  Glu  Gly                            237      Ser    Gln    Thr  Glu  Thr  Pro  Glu  Asp                            238      Ser    Gln    Thr  Glu  Lys  Leu  Glu  Asp                            239      Ser    Gln    Thr  Glu  Lys  Pro  Asp  Asp                            240      Ser    Gln    Thr  Glu  Lys  Pro  Glu  Gly                            241      Ser    Gln    Thr  Gln  Thr  Leu  Glu  Asp                            242      Ser    Gln    Thr  Gln  Thr  Pro  Asp  Asp                            243      Ser    Gln    Thr  Gln  Thr  Pro  Glu  Gly                            244      Ser    Gln    Thr  Gln  Lys  Leu  Asp  Asp                            245      Ser    Gln    Thr  Gln  Lys  Leu  Glu  Gly                            246      Ser    Gln    Thr  Gln  Lys  Pro  Asp  Gly                            247      His    Gln    Thr  Gln  Lys  Pro  Glu  Asp                            248      Ser    Trp    Thr  Gln  Lys  Pro  Glu  Asp                            249      Ser    Gln    Ala  Gln  Lys  Pro  Glu  Asp                            250      Ser    Gln    Thr  Glu  Lys  Pro  Glu  Asp                            251      Ser    Gln    Thr  Gln  Thr  Pro  Glu  Asp                            252      Ser    Gln    Thr  Gln  Lys  Leu  Glu  Asp                            253      Ser    Gln    Thr  Gln  Lys  Pro  Asp  Asp                            254      Ser    Gln    Thr  Gln  Lys  Pro  Glu  Gly                            255      Ser    Gln    Thr  Gln  Lys  Pro  Glu  Asp                            ______________________________________                                    

Other preferred proteins are those wherein Xaa at position 27 is Ala; Xaa at position 77 is Ser; Xaa at position 118 is Gly; and the amino residues at positions 97, 100, 101, 105, 106, 107, 108 and 111 are as described in Table I.

Experiments leading to the present invention were performed with five to six month old male, inbred normal ICR mice, inbred normal(ob/+), obese-diabetic mice (ob/ob) from the Jackson Laboratories (Bar Harbor, Maine) or Harlan (England), and obese-diabetic (db/db) mice.

Both normal and diabetic mice were housed three or six per plastic cage (with bedding) and water and feed were available ad libitum. The temperature of animal rooms was maintained at 23°±2°C. and lights were on from 0600 to 1800 h. Blood samples were collected from the tail vein. The most closely related biological test is, therefore, to inject the test article by any of several routes of administration (e.g., i.v., s.c., i.p., or by minipump or cannula) and then to monitor food and water consumption, body weight gain, plasma chemistry or hormones (glucose, insulin, ACTH, corticosterone, GH, T4) over various time periods. Suitable test animals include normal mice (ICR, etc.) and obese mice (ob/ob, Avy/a, KK-Ay, tubby, fat). Controls for nonspecific effects for these injections can be done using vehicle with or without test articles of similar composition in the same animal monitoring the same parameters or the test article itself in animals that are thought to lack the receptor (db/db mice, fa/fa or cp/cp rats).

Blood glucose levels were measured by a glucose oxidase method or a coupled hexokinase method. Plasma insulin was determined with radioimmunoassay kits using rat insulin as the standard. Plasma triglycerides were measured using commercial kits with glycerol as the standard.

The foregoing studies demonstrated that leptin and leptin mimetics, regulated food intake and body weight in normal ICR and genetically obese ob/ob mice. Chronic administration of leptin and leptin mimetics to ob/ob mice totally ameliorated the diabetic state of these animals showing the potential promise for these anti-diabetic proteins as a treatment for obese type II diabetics.

The compounds useful for carring out the present invention may be produced by well known chemical procedures, such as solution or solid-phase peptide synthesis, or semi-synthesis in solution beginning with protein fragments coupled through conventional solution methods. Such methods are well known in the art and may be found in general texts in the area such as H. Dugas and C. Penney, BIOORGANIC CHEMISTRY, (1981) at pages 54-92.

For example, peptides may be synthesized by solid-phase methodology utilizing an PE-Applied Biosystems 430A peptide synthesizer (commercially available from Applied Biosystems, Foster City Calif.) and synthesis cycles supplied by Applied Biosystems. t-Butoxycarbonyl (Boc)-protected amino acids and other reagents are commercially available from chemical supply houses. Sequential Boc chemistry using double couple protocols are applied to the starting p-methyl benzhydryl amine resins for the production of C-terminal carboxamides. For the production of C-terminal acids, the corresponding PAM resin is used. Arginine, Asparagine, Glutamine, Histidine and Methionine are coupled using preformed hydroxy benzotriazole esters. The following side chain protection may be used:

Arg, Tosyl

Asp, cyclohexyl or benzyl

Cys, 4-methylbenzyl

Glu, cyclohexyl

His, benzyloxymethyl

Lys, 2-chlorobenzyloxycarbonyl

Met, sulfoxide

Ser, Benzyl

Thr, Benzyl

Trp, formyl

Tyr, 4-bromo carbobenzoxy

Boc deprotection may be accomplished with trifluoroacetic acid (TFA) in methylene chloride. Formyl removal from Trp is accomplished by treatment of the peptidyl resin with 20% piperidine in dimethylformamide for 60 minutes at 4° C. Met(O) can be reduced by treatment of the peptidyl resin with TFA/dimethylsulfide/concHCl (95/5/1) at 25° C. for 60 minutes. Following the above pre-treatments, the peptides may be further deprotected and cleaved from the resin with anhydrous hydrogen fluoride containing a mixture of 10% m-cresol or m-cresol/10% p-thiocresol or m-cresol/p-thiocresol/dimethyl-sulfide. Cleavage of the side chain protecting group(s) and of the peptide from the resin is carried out at zero degrees Centigrade or below, preferably -20° C. for thirty minutes followed by thirty minutes at 0° C. After removal of the HF, the peptide/resin is washed with ether. The peptide is extracted with glacial acetic acid and lyophilized. Purification is accomplished by reverse-phase C18 chromatography (Vydac) column in 0.1% TFA with a gradient of increasing acetonitrile concentration.

One skilled in the art recognizes that the solid phase synthesis could also be accomplished using the FMOC strategy and a TFA/scavenger cleavage mixture.

Proteins useful in the presently claimed methods also may be prepared by well known recombinant DNA techniques such as those described in Maniatis, et al. (1988) Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Press, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York or Current Protocols in Molecular Biology (1989) and supplements. Techniques for making substitutional mutations at predetermined sites in DNA having a known sequence are well known, for example M13 primer mutagenesis. The mutations that might be made in the DNA encoding the present anti-diabetic proteins must not place the sequence out of reading frame and preferably will not create complementary regions that could produce secondary mRNA structure See, DeBoer, et al., European Patent Publication, 075,444 A (1983).

Recombinant methods are generally preferred if larger quantities are desired. The basic steps in the recombinant production of protein include:

a) construction of a synthetic or semi-synthetic (or isolation from natural sources) DNA encoding the desired protein,

b) integrating the coding sequence into an expression vector in a manner suitable for the expression of the protein either alone or as a fusion protein,

c) transforming an appropriate eukaryotic or prokaryotic host cell with the expression vector, and

d) recovering and purifying the recombinantly produced protein.

a. Gene Construction

Synthetic genes, the in vitro or in vivo transcription and translation of which will result in the production of the protein may be constructed by techniques well known in the art. Owing to the natural degeneracy of the genetic code, the skilled artisan will recognize that a sizable yet definite number of DNA sequences may be constructed which encode the desired proteins. In the preferred practice of the invention, synthesis is achieved by recombinant DNA technology.

Methodology of synthetic gene construction is well known in the art. For example, see Brown, et al. (1979) Methods in Enzymology, Academic Press, N.Y., Vol. 68, pgs. 109-151. The DNA sequence coding for the desired protein may be generated using conventional DNA synthesizing apparatus such as the Applied Biosystems Model 380A or 380B DNA synthesizers (commercially available from Applied Biosystems, Inc., 850 Lincoln Center Drive, Foster City, Calif. 94404).

It may desirable in some applications to modify the coding sequence of the desired protein so as to incorporate a convenient protease sensitive cleavage site, e.g., between the signal peptide and the structural protein facilitating the controlled excision of the signal peptide from the fusion protein construct.

DNA encoding the desired protein may also be created by using polymerase chain reaction (PCR) techniques. The template can be a cDNA library (commercially available from CLONETECH or STRATAGENE) or mRNA isolated from human adipose tissue. Such methodologies are well known in the art Maniatis, et al., Supra.

b. Direct Expression or Fusion Protein

The desired protein may be made either by direct expression or as fusion protein comprising the desired protein followed by enzymatic or chemical cleavage. A variety of peptidases (e.g. trypsin) which cleave a polypeptide at specific sites or digest the peptides from the amino or carboxy termini (e.g. diaminopeptidase) of the peptide chain are known. Furthermore, particular chemicals (e.g. cyanogen bromide) will cleave a polypeptide chain at specific sites. The skilled artisan will appreciate the modifications necessary to the amino acid sequence (and synthetic or semi-synthetic coding sequence if recombinant means are employed) to incorporate site-specific internal cleavage sites. See e.g., P. Carter, "Site Specific Proteolysis of Fusion Proteins", Ch. 13 in PROTEIN PURIFICATION: FROM MOLECULAR MECHANISMS TO LARGE SCALE PROCESSES, American Chemical Society, Washington, D.C. (1990).

c. Vector Construction

Construction of suitable vectors containing the desired coding and control sequences employ standard ligation techniques. Isolated plasmids or DNA fragments are cleaved, tailored, and religated in the form desired to form the plasmids required.

To effect the translation of the desired protein, one inserts the engineered synthetic DNA sequence in any of a plethora of appropriate recombinant DNA expression vectors through the use of appropriate restriction endonucleases. A synthetic coding sequence can be designed to possess restriction endonuclease cleavage sites at either end of the transcript to facilitate isolation from and integration into these expression and amplification and expression plasmids. The isolated cDNA coding sequence may be readily modified by the use of synthetic linkers to facilitate the incorporation of this sequence into the desired cloning vectors by techniques well known in the art. The particular endonucleases employed will be dictated by the restriction endonuclease cleavage pattern of the parent expression vector to be employed. The choice of restriction sites are chosen so as to properly orient the coding sequence with control sequences to achieve proper in-frame reading and expression of the desired protein.

In general, plasmid vectors containing promoters and control sequences which are derived from species compatible with the host cell are used with these hosts. The vector ordinarily carries a replication site as well as marker sequences which are capable of providing phenotypic selection in transformed cells. For example, E. coli is typically transformed using pBR322, a plasmid derived from an E. coli species (Bolivar, et al., Gene 2: 95 (1977)). Plasmid pBR322 contains genes for ampicillin and tetracycline resistance and thus provides easy means for identifying transformed cells. The pBR322 plasmid, or other microbial plasmid must also contain or be modified to contain promoters and other control elements commonly used in recombinant DNA technology.

The desired coding sequence is inserted into an expression vector in the proper orientation to be transcribed from a promoter and ribosome binding site, both of which should be functional in the host cell in which the protein is to be expressed. An example of such an expression vector is a plasmid described in Belagaje et al., U.S. Pat. No. 5,304,493, the teachings of which are herein incorporated by reference. The gene encoding A-C-B proinsulin described in U.S. Pat. No. 5,304,493 can be removed from the plasmid pRB182 with restriction enzymes NdeI and BmHI. The genes encoding the protein of the present invention can be inserted into the plasmid backbone on a NdeI/BamHI restriction fragment cassette.

d. Prokaryotic expression

In general, prokaryotes are used for cloning of DNA sequences in constructing the vectors useful in the invention. For example, E. coli K12 strain 294 (ATCC No. 31446) is particularly useful. Other microbial strains which may be used include E. coli B and E. coli X1776 (ATCC No. 31537). These examples are illustrative rather than limiting.

Prokaryotes also are used for expression. The aforementioned strains, as well as E. coli W3110 (prototrophic, ATCC No. 27325), bacilli such as Bacillus subtilis, and other enterobacteriaceae such as Salmonella typhimurium or Serratia marcescans, and various pseudomonas species may be used. Promoters suitable for use with prokaryotic hosts include the β-lactamase (vector pGX2907 ATCC 39344! contains the replicon and β-lactamase gene) and lactose promoter systems (Chang et al., Nature, 275:615 (1978); and Goeddel et al., Nature 281:544 (1979)), alkaline phosphatase, the tryptophan (trp) promoter system (vector PATH1 ATCC 37695! is designed to facilitate expression of an open reading frame as a trpE fusion protein under control of the trp promoter) and hybrid promoters such as the tac promoter (isolatable from plasmid pDR540 ATCC-37282). However, other functional bacterial promoters, whose nucleotide sequences are generally known, enable one of skill in the art to ligate them to DNA encoding the protein using linkers or adaptors to supply any required restriction sites. Promoters for use in bacterial systems also will contain a Shine-Dalgarno sequence operably linked to the DNA encoding protein.

e. Eukaryotic expression

The protein may be recombinantly produced in eukaryotic expression systems. Preferred promoters controlling transcription in mammalian host cells may be obtained from various sources, for example, the genomes of viruses such as: polyoma, Simian Virus 40 (SV40), adenovirus, retroviruses, hepatitis-B virus and most preferably cytomegalovirus, or from heterologous mammalian promoters, e.g. β-actin promoter. The early and late promoters of the SV40 virus are conveniently obtained as an SV40 restriction fragment which also contains the SV40 viral origin of replication. Fiers, et al., Nature, 273:113 (1978). The entire SV40 genome may be obtained from plasmid PBRSV, ATCC 45019. The immediate early promoter of the human cytomegalovirus may be obtained from plasmid pCMBβ (ATCC 77177). Of course, promoters from the host cell or related species also are useful herein.

Transcription of a DNA encoding the desired protein by higher eukaryotes is increased by inserting an enhancer sequence into the vector. Enhancers are cis-acting elements of DNA, usually about 10-300 bp, that act on a promoter to increase its transcription. Enhancers are relatively orientation and position independent having been found 5' (Laimins, L. et al., PNAS 78: 993 (1981)) and 3' (Lusky, M. L., et al., Mol. Cell Bio. 3: 1108 (1983)) to the transcription unit, within an intron (Banerji, J. L. et al., Cell 33: 729 (1983)) as well as within the coding sequence itself (Osborne, T. F., et al., Mol. Cell Bio. 4: 1293 (1984)). Many enhancer sequences are now known from mammalian genes (globin, RSV, SV40, EMC, elastase, albumin, a-fetoprotein and insulin). Typically, however, one will use an enhancer from a eukaryotic cell virus. Examples include the SV40 late enhancer, the cytomegalovirus early promoter enhancer, the polyoma enhancer on the late side of the replication origin, and adenovirus enhancers.

Expression vectors used in eukaryotic host cells (yeast, fungi, insect, plant, animal, human or nucleated cells from other multicellular organisms) will also contain sequences necessary for the termination of transcription which may affect mRNA expression. These regions are transcribed as polyadenylated segments in the untranslated portion of the mRNA encoding protein. The 3' untranslated regions also include transcription termination sites.

Expression vectors may contain a selection gene, also termed a selectable marker. Examples of suitable selectable markers for mammalian cells are dihydrofolate reductase (DHFR, which may be derived from the BglII/HindIII restriction fragment of pJOD-10 ATCC 68815!), thymidine kinase (herpes simplex virus thymidine kinase is contained on the BmHI fragment of vP-5 clone ATCC 2028!) or neomycin (G418) resistance genes (obtainable from pNN414 yeast artificial chromosome vector ATCC 37682!). When such selectable markers are successfully transferred into a mammalian host cell, the transfected mammalian host cell can survive if placed under selective pressure. There are two widely used distinct categories of selective regimes. The first category is based on a cell's metabolism and the use of a mutant cell line which lacks the ability to grow without a supplemented media. Two examples are: CHO DHFR⁻ cells (ATCC CRL-9096) and mouse LTK-cells (L-M(TK-) ATCC CCL-2.3). These cells lack the ability to grow without the addition of such nutrients as thymidine or hypoxanthine. Because these cells lack certain genes necessary for a complete nucleotide synthesis pathway, they cannot survive unless the missing nucleotides are provided in a supplemented media. An alternative to supplementing the media is to introduce an intact DHFR or TK gene into cells lacking the respective genes, thus altering their growth requirements. Individual cells which were not transformed with the DHFR or TK gene will not be capable of survival in nonsupplemented media.

The second category is dominant selection which refers to a selection scheme used in any cell type and does not require the use of a mutant cell line. These schemes typically use a drug to arrest growth of a host cell. Those cells which have a novel gene would express a protein conveying drug resistance and would survive the selection. Examples of such dominant selection use the drugs neomycin, Southern P. and Berg, P., J. Molec. Appl. Genet. 1: 327 (1982), mycophenolic acid, Mulligan, R. C. and Berg, P. Science 209: 1422 (1980), or hygromycin, Sugden, B. et al., Mol Cell. Biol. 5: 410-413 (1985). The three examples given above employ bacterial genes under eukaryotic control to convey resistance to the appropriate drug G418 or neomycin (geneticin), xgpt (mycophenolic acid) or hygromycin, respectively.

A preferred vector for eukaryotic expression is pRc/CMV. pRc/CMV is commercially available from Invitrogen Corporation, 3985 Sorrento Valley Blvd., San Diego, Calif. 92121. To confirm correct sequences in plasmids constructed, the ligation mixtures are used to transform E. coli K12 strain DH5a (ATCC 31446) and successful transformants selected by antibiotic resistance where appropriate. Plasmids from the transformants are prepared, analyzed by restriction and/or sequence by the method of Messing, et al., Nucleic Acids Res. 9:309 (1981).

Host cells may be transformed with the expression vectors of this invention and cultured in conventional nutrient media modified as is appropriate for inducing promoters, selecting transformants or amplifying genes. The culture conditions, such as temperature, pH and the like, are those previously used with the host cell selected for expression, and will be apparent to the ordinarily skilled artisan. The techniques of transforming cells with the aforementioned vectors are well known in the art and may be found in such general references as Maniatis, et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Press, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (1989), or Current Protocols in Molecular Biology (1989) and supplements.

Preferred suitable host cells for expressing the vectors encoding the desired proteins in higher eukaryotes include: African green monkey kidney line cell line transformed by SV40 (COS-7, ATCC CRL-1651); transformed 10 human primary embryonal kidney cell line 293,(Graham, F. L. et al., J. Gen Virol. 6: 59-72 (1977), Virology 77: 319-329, Virology 86: 10-21); baby hamster kidney cells (BHK-21(C-13), ATCC CCL-10, Virology 16: 147 (1962)); chinese hamster ovary cells CHO-DHFR⁻ (ATCC CRL-9096), mouse Sertoli cells (TM4, ATCC CRL-1715, Biol. Reprod. 23: 243-250 (1980)); african green monkey kidney cells (VERO 76, ATCC CRL-1587); human cervical epitheloid carcinoma cells (HeLa, ATCC CCL-2); canine kidney cells (MDCK, ATCC CCL-34); buffalo rat liver cells (BRL 3A, ATCC CRL-1442); human diploid lung cells (WI-38, ATCC CCL-75); human hepatocellular carcinoma cells (Hep G2, ATCC HB-8065);and mouse mammary tumor cells (MMT 060562, ATCC CCL51).

f. Yeast expression

In addition to prokaryotes, eukaryotic microbes such as yeast cultures may also be used. Saccharomyces cerevisiae, or common baker's yeast is the most commonly used eukaryotic microorganism, although a number of other strains are commonly available. For expression in Saccharomyces, the plasmid YRp7, for example, (ATCC-40053, Stinchcomb, et al., Nature 282: 39 (1979); Kingsman et al., Gene 7: 141 (1979); Tschemper et al., Gene 10: 157 (1980)) is commonly used. This plasmid already contains the trp gene which provides a selection marker for a mutant strain of yeast lacking the ability to grow in tryptophan, for example ATCC no. 44076 or PEP4-1 (Jones, Genetics 85: 12 (1977)).

Suitable promoting sequences for use with yeast hosts include the promoters for 3-phosphoglycerate kinase (found on plasmid pAP12BD ATCC 53231 and described in U.S. Pat. No. 4,935,350, Jun. 19, 1990) or other glycolytic enzymes such as enolase (found on plasmid pAC1 ATCC 39532), glyceraldehyde-3-phosphate dehydrogenase (derived from plasmid pHcGAPC1 ATCC 57090, 57091), zymomonas mobilis (U.S. Pat. No. 5,000,000 issued Mar. 19, 1991), hexokinase, pyruvate decarboxylase, phosphofructokinase, glucose-6-phosphate isomerase, 3-phosphoglycerate mutase, pyruvate kinase, triosephosphate isomerase, phosphoglucose isomerase, and glucokinase.

Other yeast promoters, which are inducible promoters having the additional advantage of transcription controlled by growth conditions, are the promoter regions for alcohol dehydrogenase 2, isocytochrome C, acid phosphatase, degradative enzymes associated with nitrogen metabolism, metallothionein (contained on plasmid vector pCL28XhoLHBPV ATCC 39475, U.S. Pat. No. 4,840,896), glyceraldehyde 3-phosphate dehydrogenase, and enzymes responsible for maltose and galactose (GAL1 found on plasmid pRY121 ATCC 37658) utilization. Suitable vectors and promoters for use in yeast expression are further described in R. Hitzeman et al., European Patent Publication No. 73,657A. Yeast enhancers such as the UAS Gal from Saccharomyces cerevisiae (found in conjunction with the CYC1 promoter on plasmid YEpsec--hI1beta ATCC 67024), also are advantageously used with yeast promoters.

The present invention provides a method for treating obese type II diabetics. The method comprises administering an effective amount of a leptin or leptin mimetic in a dose between about 1 and 10,000 μg/kg. A preferred dose is from about 20 to 1,000 μg/kg. A more preferred dose is from about 50 to 500 μg/kg. A typical daily dose for an adult human is from about 0.5 to 100 mg. In practicing this method, anti-diabetic proteins can be administered in a single daily dose or in multiple doses per day. The treatment regime may require administration over extended periods of time. The amount per administered dose or the total amount administered will be determined by the physician and depend on such factors as the mass of the patient, the age and general health of the patient and the tolerance of the patient to the compound.

In the practice of the present invention, it is useful, but not essential to prepare pharmaceutical formulations comprising anti-diabetic proteins. Such proteins, preferably in the form of a pharmaceutically acceptable salt, can be formulated for parenteral administration. For example, compounds can be admixed with conventional pharmaceutical carriers and excipients. The compositions comprising desired proteins contain from about 0.1 to 90% by weight of the active protein, preferably in a soluble form, and more generally from about 0.1 to 1.0%. Furthermore, the present proteins may be administered alone or in combination with other anti-obesity agents or agents useful in treating diabetes.

For intravenous use, the protein is administered in commonly used intravenous fluids and administered by infusion. For intramuscular preparations, a sterile formulation, preferably a suitable soluble salt form of the protein, for example the hydrochloride salt, can be dissolved and administered in a pharmaceutical diluent such as pyrogen-free water or physiological saline. A suitable insoluble form of the compound may be prepared and administered as a suspension in an aqueous base or a pharmaceutically acceptable oil base, e.g. an ester of a long chain fatty acid such as ethyl oleate.

In a preferred embodiment, the present invention provides a method for treating obese type II diabetics with low leptin levels, though diabetic patients with high endogenous leptin levels may also benefit from the presently claimed methods. Methods for assaying serum and plasma leptin levels may be accomplished using standard antibody-based methodologies. Leptin assay kits are also commercially available from Linco Research, Inc. (14 Research Park Dr., St Louis, Mo. 63304)

Treating obese type II diabetics having leptin levels between 0 and 80 ng/ml is preferred. More preferred is to treat obese type II diabetics having leptin levels between 0 and 50 ng/ml. More highly preferred is to treat obese type II diabetics having leptin levels between 0 and 30 ng/ml. Most preferred is to treat obese type II diabetics having leptin levels between 0 and 15 ng/ml.

By way of illustration, the following examples are provided to help describe how to make and practice the various embodiments of the invention. These example are in no way meant to limit the scope of the invention.

EXAMPLE 1

A DNA sequence encoding the following protein sequence:

Met-Arg-SEQ ID NO:4.

was obtained using standard PCR methodology from a human fat cell library (commercially available from CLONETECH). Briefly, degenerate primers were designed based on the published amino acid sequence of the human ob gene. The primers were prepared for use in polymerase chain reaction (PCR) amplification methods using a Model 380A DNA synthesizers (PE-Applied Biosystems, Inc., 850 Lincoln Center Drive, Foster City, CA 94404). Forward primers OB.F1M (5-GG GG CAT ATG AGG GTA CCT ATC CAG AAA GTC CAG GAT GAC AC)and OB.F2H (5-GG GG CAT ATG AGG GTA CCC ATC CAG AAG GTG CAG GAC GA)(and reverse primers OB.R1M (5-GG GG GGATC GAT AAT TTA GCA TCC AGG GCT AAG ATC CAA CTG CCA AAG CAT) and OB.R2H (5-GG GG GGATC CTA TTA GCA CCC GGG AGA CAG GTC CAG CTG CCA CAA CAT) were mixed together with a PCR-ready human fat cell CDNA as the template (Clontech Laboratories, Inc., 4030 Fabian Way, Palo Alto, Calif. 94303; Item #7128-1).

The 2 sets of PCR amplifications were performed using 2.5 units of Amplitag DNA polymerase (Perkin Elmer Cetus) or 2 units of Vent DNA polymerase (New England Biolabs) in 100 uL reactions. PCR reactions contained 1 uL of human fat cell cDNA, 10 pmol of each primer (all four were mixed). The following conditions were used for "Touchdown PCR": 2 cycles: 94° C.×30 sec, 60° C.×30 sec, 72° C.×45 sec 2 cycles: 94° C.×30 sec, 56° C. ×30 sec, 72° C.×45 sec; 2cycles: 94° C.×30 sec. 52° C.×30 sec, 72C.×45 sec; 2cycles: 94° C.×30 sec, 48° C.×30 sec, 72C.×45 sec; 2 cycles: 94° C.×30 sec, 44° C.×30 sec, 72° C.×45 sec: 28 cycles 94° C.×30 sec, 52° C.×30 sec, 72° C.×45 sec

The resultant PCR reactions products were run on a 1% agarose gel and a band of an approximate 450 bp in size was visualized by ethidium bromide staining. This band was present in both sets of PCR reactions. The bands 20 were excised and reamplified using above conditions in 30 cycles (94×30 sec, 52×30, 72×45). The PCR product obtained using Vent DNA polymerase was gel purified and cloned into a pCR-SCRIPT cloning vector (Stratagene). The vector was then used to transform E. coli cells. Plasmid DNA was isolated from 20 white colonies of E. coli and samples from three clones were sequenced. Two such colonies, E. coli DH10B/pOJ717 and E. coli DH10B/pOJ718 were deposited with the Northern Regional Research Laboratories (NRRL) under terms of the Budapest Treaty and are available under Accession Numbers B-21408 and B-21409 respectively.

EXAMPLE 2 Vector Construction

A plasmid containing the DNA sequence encoding a desired protein is constructed to include NdeI and BamHI restriction sites. The plasmid carrying the cloned PCR product is digested with NdeI and BamHI restriction enzymes. The small˜450bp fragment is gel-purified and ligated into the vector pRB182 from which the coding sequence for A-C-B proinsulin is deleted. The ligation products are transformed into E. coli DH10B (commercially available) and colonies growing on tryptone-yeast plates supplemented with 10 μg/mL of tetracycline are analyzed. Plasmid DNA is isolated, digested with NdeI and BamHI and the resulting fragments are separated by agarose gel electrophoresis. Plasmids containing the expected˜450bp NdeI to BamHI fragment are kept. E. coli B BL21 (DE3) are transformed with this second plasmid expression suitable for culture for protein production.

The techniques of transforming cells with the aforementioned vectors are well known in the art and may be found in such general references as Maniatis, et al., MOLECULAR CLONING: A LABORATORY MANUAL, Cold Spring Harbor Press, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York (1988), or CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, (F. Ausabel, ed., 1989) and supplements thereof. The techniques involved in the transformation of E. coli cells used in the preferred practice of the invention as exemplified herein are well known in the art. The precise conditions under which the transformed E. coli cells are cultured is dependent on the nature of the E. coli host cell line and the expression or cloning vectors employed. For example, vectors which incorporate thermoinducible promoter-operator regions, such as the c1857 thermoinducible lambda-phage promoter-operator region, require a temperature shift from about 30° C. to about 40° C. in the culture conditions so as to induce protein synthesis.

In the preferred embodiment of the invention E. coli K12 RV308 cells are employed as host cells but numerous other cell lines are available such as, but not limited to, E. coli K12 L201, L687, L693, L507, L640, L641, L695, L814 (E. coli B). The transformed host cells are then plated on appropriate media under the selective pressure of the antibiotic corresponding to the resistance gene present on the expression plasmid. The cultures are then incubated for a time and temperature appropriate to the host cell line employed.

Proteins which are expressed in high-level bacterial expression systems characteristically aggregate in granules or inclusion bodies which contain high levels of the overexpressed protein. See, e.g., Kreuger et al., PROTEIN FOLDING, (Gierasch and King, eds., 1990) at pages 136-142, American Association for the Advancement of Science Publication No. 89-18S, Washington, D.C. Such protein aggregates must be solubilized to provide further purification and isolation of the desired protein product. Id. A variety of techniques using strongly denaturing solutions such as guanidinium-HCl and/or weakly denaturing solutions such as dithiothreitol (DTT) are used to solubilize the proteins.

Gradual removal of the denaturing agents (often by dialysis) in a solution allows the denatured protein to assume its native conformation. The particular conditions for denaturation and folding are determined by the particular protein expression system and/or the protein in question.

Preferably, the present proteins are expressed as Met-Arg-SEQ ID NO: X so that the expressed proteins may be readily converted to the desired protein with cathepsin C (also known as diaminopeptidase). The purification of proteins is by techniques known in the art and includes reverse phase chromatography, affinity chromatography, and size exclusion chromatography.

The desired proteins contain two cysteine residues. Thus, a di-sulfide bond may be formed to stabilize the protein. The present invention includes proteins wherein the Cys at position 96 is crosslinked to Cys at position 146 as well as those proteins without such di-sulfide bonds.

In addition the proteins useful in the present invention may exist, particularly when formulated, as dimers, trimers, tetramers, and other multimers. Such multimers are included within the scope of the present invention.

    __________________________________________________________________________     SEQUENCE LISTING                                                               (1) GENERAL INFORMATION:                                                       (iii) NUMBER OF SEQUENCES: 12                                                  (2) INFORMATION FOR SEQ ID NO:1:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 146 amino acids                                                    (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: protein                                                    (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:                                        ValProIleGlnLysValGlnAspAspThrLysThrLeuIleLysThr                               151015                                                                         IleValThrArgIleAsnAspIleSerHisThrXaaSerValSerSer                               202530                                                                         LysGlnLysValThrGlyLeuAspPheIleProGlyLeuHisProIle                               354045                                                                         LeuThrLeuSerLysMetAspGlnThrLeuAlaValTyrGlnGlnIle                               505560                                                                         LeuThrSerMetProSerArgAsnValIleGlnIleSerAsnAspLeu                               65707580                                                                       GluAsnLeuArgAspLeuLeuHisValLeuAlaPheSerLysSerCys                               859095                                                                         HisLeuProGlnAlaSerGlyLeuGluThrLeuGluSerLeuGlyGly                               100105110                                                                      ValLeuGluAlaSerGlyTyrSerThrGluValValAlaLeuSerArg                               115120125                                                                      LeuGlnGlySerLeuGlnAspMetLeuGlnGlnLeuAspLeuSerPro                               130135140                                                                      GlyCys                                                                         145                                                                            (2) INFORMATION FOR SEQ ID NO:2:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 146 amino acids                                                    (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: protein                                                    (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:                                        ValProIleTrpArgValGlnAspAspThrLysThrLeuIleLysThr                               1510                                                                           IleValThrArgIleSerAspIleSerHisMetGlnSerValSerSer                               202530                                                                         LysGlnArgValThrGlyLeuAspPheIleProGlyLeuHisProVal                               354045                                                                         LeuSerLeuSerLysMetAspGlnThrLeuAlaIleTyrGlnGlnIle                               505560                                                                         LeuThrSerLeuProSerArgAsnValIleGlnIleSerAsnAspLeu                               65707580                                                                       GluAsnLeuArgAspLeuLeuHisLeuLeuAlaSerSerLysSerCys                               859095                                                                         ProLeuProGlnAlaArgAlaLeuGluThrLeuGluSerLeuGlyGly                               100105110                                                                      ValLeuGluAlaSerLeuTyrSerThrGluValValAlaLeuSerArg                               115120125                                                                      LeuGlnGlyAlaLeuGlnAspMetLeuArgGlnLeuAspLeuSerPro                               130135140                                                                      GlyCys                                                                         145                                                                            (2) INFORMATION FOR SEQ ID NO:3:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 146 amino acids                                                    (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: protein                                                    (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:                                        ValProIleCysLysValGlnAspAspThrLysThrLeuIleLysThr                               151015                                                                         IleValThrArgIleAsnAspIleSerHisThrXaaSerValSerSer                               202530                                                                         LysGlnArgValThrGlyLeuAspPheIleProGlyLeuHisProLeu                               354045                                                                         LeuSerLeuSerLysMetAspGlnThrLeuAlaIleTyrGlnGlnIle                               505560                                                                         LeuThrSerLeuProSerArgAsnValValGlnIleSerAsnAspLeu                               65707580                                                                       GluAsnLeuArgAspLeuLeuHisLeuLeuAlaAlaSerLysSerCys                               859095                                                                         ProLeuProGlnValArgAlaLeuGluSerLeuGluSerLeuGlyVal                               100105110                                                                      ValLeuGluAlaSerLeuTyrSerThrGluValValAlaLeuSerArg                               115120125                                                                      LeuGlnGlySerLeuGlnAspMetLeuArgGlnLeuAspLeuSerPro                               130135140                                                                      GlyCys                                                                         145                                                                            (2) INFORMATION FOR SEQ ID NO:4:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 146 amino acids                                                    (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: protein                                                    (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:                                        ValProIleGlnLysValGlnAspAspThrLysThrLeuIleLysThr                               151015                                                                         IleValThrArgIleAsnAspIleSerHisXaaXaaSerValSerSer                               202530                                                                         LysGlnLysValThrGlyLeuAspPheIleProGlyLeuHisProIle                               354045                                                                         LeuThrLeuSerLysMetAspGlnThrLeuAlaValTyrGlnGlnIle                               505560                                                                         LeuThrSerMetProSerArgAsnValIleGlnIleSerAsnAspLeu                               657075                                                                         GluAsnLeuArgAspLeuLeuHisValLeuAlaPheSerLysSerCys                               859095                                                                         HisLeuProTrpAlaSerGlyLeuGluThrLeuAspSerLeuGlyGly                               100105110                                                                      ValLeuGluAlaSerGlyTyrSerThrGluValValAlaLeuSerArg                               115120125                                                                      LeuGlnGlySerLeuGlnAspMetLeuTrpGlnLeuAspLeuSerPro                               130135140                                                                      GlyCys                                                                         145                                                                            (2) INFORMATION FOR SEQ ID NO:5:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 146 amino acids                                                    (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: protein                                                    (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:                                        ValProIleGlnLysValGlnSerAspThrLysThrLeuIleLysThr                               151015                                                                         IleValThrArgIleAsnAspIleSerHisThrGlnSerValSerSer                               202530                                                                         LysGlnArgValThrGlyLeuAspPheIleProGlyLeuHisProVal                               354045                                                                         LeuThrLeuSerGlnMetAspGlnThrLeuAlaIleTyrGlnGlnIle                               50560                                                                          LeuIleAsnLeuProSerArgAsnValIleGlnIleSerAsnAspLeu                               65707580                                                                       GluAsnLeuArgAspLeuLeuHisLeuLeuAlaPheSerLysSerCys                               859095                                                                         HisLeuProLeuAlaSerGlyLeuGluThrLeuGluSerLeuGlyAsp                               100105110                                                                      ValLeuGluAlaSerLeuTyrSerThrGluValValAlaLeuSerArg                               115120125                                                                      LeuGlnGlySerLeuGlnAspMetLeuTrpGlnLeuAspLeuSerPro                               130135140                                                                      GlyCys                                                                         145                                                                            (2) INFORMATION FOR SEQ ID NO:6:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 146 amino acids                                                    (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: protein                                                    (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6:                                        ValProIleGlnLysValGlnAspAspThrLysThrLeuIleLysThr                               151015                                                                         IleValThrArgIleAsnAspIleSerHisThrGlnSerValSerAla                               202530                                                                         ArgGlnArgValThrGlyLeuAspPheIleProGlyLeuHisProIle                               354045                                                                         LeuSerLeuSerLysMetAspGlnThrLeuAlaValTyrGlnGlnIle                               505560                                                                         LeuThrSerLeuProSerGlnAsnValLeuGlnIleAlaHisAspLeu                               657075                                                                         GluAsnLeuArgAspLeuLeuHisLeuLeuAlaPheSerLysSerCys                               859095                                                                         SerLeuProGlnThrArgGlyLeuGlnLysProGluSerLeuAspGly                               100105110                                                                      ValLeuGluAlaSerLeuTyrSerThrGluValValAlaLeuSerArg                               115120125                                                                      LeuGlnGlySerLeuGlnAspIleLeuGlnGlnLeuAspLeuSerPro                               130135140                                                                      GluCys                                                                         145                                                                            (2) INFORMATION FOR SEQ ID NO:7:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 146 amino acids                                                    (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: protein                                                    (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7:                                        ValProIleGlnLysValGlnAspAspThrLysThrLeuIleLysThr                               151015                                                                         IleValThrArgIleXaaAspIleSerHisXaaXaaSerValSerSer                               202530                                                                         LysGlnLysValThrGlyLeuAspPheIleProGlyLeuHisProIle                               354045                                                                         LeuThrLeuSerLysXaaAspGlnThrLeuAlaValTyrGlnGlnIle                               505560                                                                         LeuThrSerXaaProSerArgXaaValIleGlnIleXaaAsnAspLeu                               65707580                                                                       GluAsnLeuArgAspLeuLeuHisValLeuAlaPheSerLysSerCys                               859095                                                                         HisLeuProTrpAlaSerGlyLeuGluThrLeuAspSerLeuGlyGly                               100105110                                                                      ValLeuGluAlaSerXaaTyrSerThrGluValValAlaLeuSerArg                               115120125                                                                      LeuGlnGlySerLeuGlnAspMetLeuTrpGlnLeuAspLeuSerPro                               130135140                                                                      GlyCys                                                                         145                                                                            (2) INFORMATION FOR SEQ ID NO:8:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 146 amino acids                                                    (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: protein                                                    (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8:                                        ValProIleGlnLysValGlnAspAspThrLysThrLeuIleLysThr                               151015                                                                         IleValThrArgIleAsnAspIleSerHisXaaGlnSerValSerSer                               202530                                                                         LysGlnLysValThrGlyLeuAspPheIleProGlyLeuHisProIle                               354045                                                                         LeuThrLeuSerLysMetAspGlnThrLeuAlaValTyrGlnGlnIle                               505560                                                                         LeuThrSerMetProSerArgAsnValIleGlnIleXaaAsnAspLeu                               65707580                                                                       GluAsnLeuArgAspLeuLeuHisValLeuAlaPheSerLysSerCys                               859095                                                                         HisLeuProTrpAlaSerGlyLeuGluThrLeuAspSerLeuGlyGly                               100105110                                                                      ValLeuGluAlaSerXaaTyrSerThrGluValValAlaLeuSerArg                               115120125                                                                      LeuGlnGlySerLeuGlnAspMetLeuTrpGlnLeuAspLeuSerPro                               130135140                                                                      GlyCys                                                                         145                                                                            (2) INFORMATION FOR SEQ ID NO:9:                                               (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 42 base pairs                                                      (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: cDNA                                                       (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9:                                        GGGGCATATGAGGGTACCTATCCAGAAAGTCCAGGATGACAC42                                   (2) INFORMATION FOR SEQ ID NO:10:                                              (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 39 base pairs                                                      (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: cDNA                                                       (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10:                                       GGGGCATATGAGGGTACCCATCCAGAAGGTGCAGGACGA39                                      (2) INFORMATION FOR SEQ ID NO:11:                                              (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 51 base pairs                                                      (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: cDNA                                                       (xi) SEQUENCE DESCRIPTION: SEQ ID NO:11:                                       GGGGGGATCGATAATTTAGCATCCAGGGCTAAGATCCAACTGCCAAAGCAT51                          (2) INFORMATION FOR SEQ ID NO:12:                                              (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 48 base pairs                                                      (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                           (ii) MOLECULE TYPE: cDNA                                                       (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12:                                       GGGGGGATCCTATTAGCACCCGGGAGACAGGTCCAGCTGCCACAACAT48                             __________________________________________________________________________ 

I claim:
 1. A method of treating or ameliorating diabetes mellitus, in a patient in need thereof, which comprises administering to an obese type II diabetic an effective amount of leptin, a leptin mimetic, or a pharmaceutically acceptable salt thereof.
 2. A method of claim 1 wherein said leptin or leptin mimetic is selected from the group consisting of ##STR7## wherein: Xaa at position 28 is Gln or absent; (SEQ ID NO:1) ##STR8## wherein Xaa at position 28 is Gln or absent; (SEQ ID NO:3) ##STR9## wherein: Xaa at position 27 is Thr or Ala; andXaa at position 28 is Gln or absent; (SEQ ID NO:4) ##STR10## wherein: Xaa at position 22 is Asn, Asp or Glu; Xaa at position 27 is Thr or Ala; Xaa at position 28 is Gln, Glu, or absent; Xaa at position 54 is Met or Ala; Xaa at position 68 is Met or Leu; Xaa at position 72 Asn, Asp or Glu; Xaa at position 77 is Ser or Ala; Xaa at position 118 is Gly or Leu;said protein having at least one substitution selected from the group consisting of: His at position 97 is replaced with Ser or Pro; Trp at position 100 is replaced with Gln, Ala or Leu; Ala at position 101 is replaced with Thr or Val; Ser at position 102 is replaced with Arg; Gly at position 103 is replaced with Ala; Glu at position 105 is replaced with Gln; Thr at position 106 is replaced with Lys or Ser; Leu at position 107 is replaced with Pro; Asp at position 108 is replaced with Glu; orGly at position 111 is replaced with Asp; and, (SEQ ID NO:7) ##STR11## wherein: Xaa at position 27 is Thr or Ala; Xaa at position 77 is Ser or Ala; Xaa at position 118 is Gly or Leu;said protein having at least one substitution, preferably having one to five substitutions and, most preferably, one to two substitutions selected from the group consisting of: His at position 97 is replaced with Ser; Trp at position 100 is replaced with Gln; Ala at position 101 is replaced with Thr; Glu at position 105 is replaced with Gln; Thr at position 106 is replaced with Lys; Leu at position 107 is replaced with Pro; Asp at position 108 is replaced with Glu; or Gly at position 111 is replaced with Asp, (SEQ ID NO:8)or a pharmaceutically acceptable salt or solvate thereof.
 3. A method of claim 1 wherein said obese type II diabetic has endogenous leptin levels in the range of 0 to 80 ng/ml.
 4. A method of claim 1 wherein said obese type II diabetic has endogenous leptin levels in the range of 0 to 50 ng/ml.
 5. A method of claim 1 wherein said obese type II diabetic has endogenous leptin levels in the range of 0 to 30 ng/ml.
 6. A method of claim 1 wherein said obese type II diabetic has endogenous leptin levels in the range of 0 to 15 ng/ml.
 7. A method for treating or ameliorating diabetes mellitus which comprises administering to an afflicted patient a leptin or leptin mimetic. 